The series, or source, termination for LVCMOS outputs is the most popular due to its minimal component count and easy calculation. Simply subtract the driver’s output impedance, Ro, from the trace impedance, Zo, to calculate the series resistance, Rs, needed on the termination. The Rs termination resistor should be placed near the driver, before the transmission line, to minimize any waveform reflections. For additional flexibility, an optional series resistor or capacitor to ground, after the transmission line near the receiver may be added. This additional component helps to control any overshoot in the signal or slow down edge rates.